Exploring Of The Origination Of Nestin-immunoreactive Neurons In The Basal Forebrain

Background The basal forebrain that made up of medial septum and diagonal band nucleuses, contains cholinergic, GABAergic, glutamatergic and other neurons..Cholinergic neurons project to hippocampus and cerebral cortex, and are closely related with the functions of learning and memory and diseases such as senile dementia. Recent studies discovered that there is a group of nestin-immunoreactive(nestin-ir) neurons in the basal forebrain, and demonstrated these neurons are cholinergic neurons. Compared with nestin negative cholinergic neurons, nestin-ir neurons have stronger neural plasticity. But the origination of these neurons is not clear, they may be new born neuron, or the mature cholinergic neurons expressing nestin in a special state.Objective This research used 5-ethyny-2’-deoxyuridine(Ed U) incorporation and nestin immunofluorescence, nestin and doublecortin(DCX) routine immunohistochemical method to study relationship between nestin-ir neurons and newborn neurons, so as to explore the origination of nestin-ir neurons in the basal forebrain, to provide bases for further functional studying of the nestin-ir neurons in the basal forebrain and to enhance learning and memory ability by altering nestin expression.Methods The double stain study of Ed U and nestin immunofluorescence:Five BALB/c mice were peritoneal injected of Ed U, 100 mg/kg body weight. Ninety six hours after injection, routine paraformaldehyde perfusing fixation was performed,hippocampus and basal forebrain were harvested and frozen sectioned. Nestin immunofluorescence and Ed U fluorescence staining were performed to study therelationship between nestin-ir neurons and Ed U positive cells. Research on the relationship between nestin and DCX immunoreactive neurons: Five 2 month-old female SD rats were perfused and fixed, nestin and DCX immunohistochemistry of hippocampus and basal forebrain were made, to observe the relationship between nestin-ir neurons and DCX immunoreative neurons.Results Ed U positive neurons mainly distributed at dentate gyrus of hippocampus,ependyma and subventricular zone of the lateral ventricle, but did not find at the medial septum,vertical and horizontal limbs of the diagonal band nucleus.Nestin-ir neurons were mainly distributed in the medial septum, vertical and horizontal limbs of diagonal band nucleus. No colocalization of nestin-ir neurons and Ed U positive neurons was found. Nestin and DCX routine immunohistochemical experiments discovered nestin-ir neurons were mainly distributed in the medial septal nucleus and nucleus of the diagonal band. Eependyma and dentate gyrus of the hippocampus also distributed nestin-ir cells. DCX immunoreactive cells were mainly distributed in the hippocampal dentate gyrus. These cells have clear boundary and long processes. There were clumped DCX immunoreactive cells at ependyma of the anterior lateral ventricle. At subependymal zone also scattered few DCX positive cells,but no obvious DCX immunoreactive cells at medial septal nucleus and diagonal band nucleus. In other words, there were nestin-ir neurons, but no DCX positive neurons at the medial septum and nucleus of diagonal band.Conclusion The nestin-ir neurons in the basal forebrain have no double stain with Ed U positive cells, no colocalization with DCX positive neurons. So the nestin-ir neurons in the basal forebrain are not newborn neurons. They may be cholinergic neurons on a special functional stage.